Process of improving certain magnetic qualities of a magnetic body.



. n Drawin Application fled February a1,

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.Be it known that I, Ronnn'r A. Hanrmrn, a subject of the King of Great Britain, residing at Parkhead, Shefiield, England, have invented a certain new and useful Improvement in Processes for Improving .Certaiir Magnetic Qualities of a Magnetic Body, of e which the following is a specification. I]

The invention is a process for improving certain magnetic qualifies of a magnetic; body containing iron.

I have discovered that the permeability may be increased and the hysteresis actibn reduced of a magnetic body containing iron and low in carbon, by heating said body to a point within bounds known as the gamma range of temperature which brings about a certain conditioner structure of the iron present, and then cooling the same preferably slowly. This heating and cooling may beieifected in any suitable way. By gamma range of temperature is meant that range of temperature existing above the third critical point most definitely shown in ordinary carbon steels when heated] A dia 1 gram accurately illustrating this point is given. by Messrs; Arnold and McWilliam in,

their paper on" the thermal transformations of carbon steels published in the, Journal of the Iron and Steel Institute 1905, Vol. 2. Diagram 2 in this paper. shows the critical point for a certain carbon steel at about 870- centigrade. The variations from this'temperature for varying carbon contents are discussed in other portions of'the same paper. his to be pointed out that thepres: f ence of constitutents other than carbon,j also 7 Influence the lower limit of-temperature of the gamma state. There canybe no ambigas to the-,me'a. of the termabove vd ed, sinceit-is'wielyused in'c'ontemporaneous metallurgical literature.

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1000, semi macaw. re ew my a, mo, 559,828.

. In U. ted'to me Novemberfl'l, 1906, I have set iorth an alloy of iron and silicon, which is S. Letters Patent No.1 836, l 54;;-

i an.

one specific magnetic body within the present disclosure, treated by heating to -a point within the gamma range as herein set, I forth. In'U. S. Letters Patent No. 836,497,

granted to me November 20, 1906, I have set .forth an iron-silicon-aluminum alloy, which is another specific magnetic body, similarly treated, and in U. S. Letters Patent No. 837,682, granted to me-December 4, 1906, I have described'still-another such specific magnetic body, name1y,-an iron-silicon-manganese alloy treated in like manner.

I claim:

, 1.:The herein described I of in decreasing the hysteresls'actlon-oi a'mag-' creasing the permeabili and resistance and 'netic body, which consists in heating said body-to-a point within bounds kn as e I 'ig a range and thenlcooling 2. The 'hereindescribed ces s f i range and then slowly cooling.-

3. The herein described process signature in presence of two Y 1 ROBERT A; HADFIEE'D.

Witnessesr' W G. H. Hnnsonn, E. Romans,

of in creasing the permeability and reducing the 1 hysteresis -.action of a magnetic-body con taining iron and being low-in carbon, which" consists in heating the'body to 'a'point-within bounds known as.-the .gammarange 1 I and then--cooling',.substantial1y-as described.

In testimony whereof-.1 have aflixed my 65. creasing the permeability an resistance and reducing the hysteresis action of .alnagne ic' bodycontaining iron and being low in car-g bon, which consists in heating the. body to a point within bounds known as the 'gamma. .g 

